


good boy

by tsunderestorm



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Bathing/Washing, Established Relationship, F/M, Light Dom/sub, Master/Pet, Praise Kink, Vaginal Sex
Language: English
Status: Completed
Published: 2019-10-02
Updated: 2019-10-02
Packaged: 2020-11-15 08:23:10
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,464
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20863175
Author URL: https://archiveofourown.org/users/tsunderestorm/pseuds/tsunderestorm
Summary: Sylvain is Byleth’s good puppy, and he deserves a reward.





	good boy

**Author's Note:**

  * For [MicchiKureshima](https://archiveofourown.org/users/MicchiKureshima/gifts).

> This is tame as far as petplay goes, mostly because I don’t think Sylvain is _that_ kinky. Thank you to my amazing friend Sam for asking me to write this, it was so incredibly fun!!!

Blessedly, the baths are deserted this late at night - no footsteps disturb the collected puddles around the edge of the bath, no voices break the silent stillness, the steam rising from the hot water is the only company they have. There is no one to interrupt them… which is perfect. Her puppy needs a reward. He’s been so good all day… following each and every one of her orders to the letter, sending perfectly executed curses and spells from beside her, lance at the ready and ever vigilant. When the battle had ended and they’d applauded their lack of losses, he’d turned to look at her and his eyes had pleaded more convincingly than words could ever convey.

It’s not as if this is all for him, either. Goddess, she’s been pent-up… with Dimitri in the state he’s in these days, he’s more keen to pace around like a wild animal than take part in _anything_ she has to offer, and while Felix is good for the occasional bout of post-spar fucking, he’s just so prickly. Mercie was always an option… but she was so tender, so eager to play mommy and soothe, and Byleth doesn’t need that right now. She needs to take what she wants, and so Sylvain is the only option, eager to please and to be controlled and with a nice, thick, dick besides.

He’s sitting in the water when she gets there, arms outstretched and head tipped back against the edge. She takes a second to admire him, lovingly staring at the perfect sculpt of his jaw, his thick neck with love bites ringing it like a collar, his arms honed by years of handling a lance. The hair on his chest is a rich, deep auburn, sweat beading on his tits from the heat of the bathwater, dusky nipples barely visible above the surface of the water. She’ll suck those, she knows, leave him keening and mewling against her.

Just _looking_ at him makes her cunt throb.

She disrobes quickly, stepping out of her clothes and into the water. His eyes snap open immediately, sitting up just a little straighter, more attentive. (If he had a tail, she thinks, it’d be wagging.) Straddling his waist is the first of his rewards, settling her thick thighs on either side of his on the ledge along the bath’s edge. His cock is halfway there already, a lazy hard-on that she can’t help but touch, curling her fingers around it and cooing, “How cute.”

Sylvain whimpers, a flush high on his cheeks making his face as red as his hair. It isn’t the heat from the bath, Byleth knows, and her fingers leave his cock as quickly as they’d come, ghosting across his stomach enough to tease, to titillate, to make him crave it just a little bit before she gives it to him. She doesn’t want to make him wait too long… not when he’s been so good. Just the barest whimper of _please _makes her stop the teasing and slowly, her finger trails up the underside of his cock before brushing over the slit. Sylvain shudders. He wants that; that tiny, hot flash of pleasure from her against his aching cock.

“Hey, Byleth…?” Sylvain asks, nuzzling into her tits positioned so temptingly before his face, a hand reaching beneath the water’s surface to grasp her wrist gently, slowing the movements of her generous hand to drag out the touches out but not stopping her. He never wants to stop her, just wants to make it last. It’s funny, he thinks, how guys are always so eager to get it in when that’s not even the fun part, not when the attention and praise… _goddess, _the praise made heat pool in his belly more than anything else ever could. “Would you wash my hair? I’ve been good.”

She could take him inside of her right now. Goddess knows she’s slick enough, and a few expert jerks of her hand could work him to stiffness. She could take what they both want right now. Press her tits to his face and let him suck sweetly on her nipples, let his cock slide in until it’s snugly seated inside her as she washes the day’s battles out of his hair, but he’s just so patient and pliant like this. If it goes too fast, it’s over, and she’s been with Sylvain enough times now to know that’s the last thing he wants. Sylvain is never rude, never impatient even when he’s hard and wanting, but there’s something so special about him when he’s like this, as easily controlled as if she had a leash and a collar around his neck. She wants to savor it for as long as she can.

“You’re always good,” she says, smoothing his lopsided fall of messy hair back from his flushed face. She leans forward and reaches for the cup she’d spirited away from the dining hall, moaning when he presses the lightest of kisses to the side of her breast. “It’s cute! You want so badly to be good for teacher.”

He ducks his head when she raises the now-filled cup, acquiescing to the fall of warm water cascading over his head to wet his hair, humming happily. His skin glistens in the low lamplight, making him look ethereal, like he’s the god and she’s merely a mortal. She rubs the bar of soap between her hands as he presses his damp cheek to her full tits, working up a richly scented lather that she works into his hair with nimble fingers. He moans, that sound of simple bliss somehow more lewd than any sound she’s ever heard from the conventional pleasure of his cock buried inside of her. It rips through her like a shock wave, the emptiness in her cunt an absolute ache, and she moans as she works her fingertips over his scalp, soaping up every strand of his hair.

“Byleth…” he whimpers, hands on her hips. She’s prettier than the goddess whose power she carries: a vision in the low light, with her soft, perfect tits and her pretty skin with its storyboard of scars. He wants her. He needs her. He wants to be everything for her: her friend, her lover, her good puppy… fuck, someday, her husband. He’d never wanted that once in his life.

“My good puppy…” she says, patting his head, completely endeared by the way he moves his head against her hand in something like relief, seeking the touch. “You like this, don’t you…?” she asks as fastens his lips fully around one slick, sweet nipple. He nods, sucking it until its hard and eager against his tongue, and when he pulls back, he answers her question with one of his own.

Pupils blown wide with pleasure, he looks up and asks, “Does that feel good?”

Byleth nods, moving so she’s pressing him back against the edge of the tub, urging his mouth back to her nipple and working a knee between his legs. She can feel his cock against her, rubbing her cunt down against his muscular thigh in a hungry attempt for friction and shuddering when he presses back, ever obedient. “So well trained!” she teases.

Sylvain hums happily, turning his attention to her other nipple, sucking lazily and closing his eyes. He could probably come like this, she thinks, sucking on her tits with his cock doing little else but pressing against her belly… she thinks that’s cute, he knows, and he doesn’t mind. 

“You’re so beautiful,” Byleth praises, and it’s not a false compliment. Sylvain is exquisite - gorgeous red hair and warm eyes, long lashes that brush his handsome cheeks, a smile that splits his face when it’s sincere (and for her, it always is), soft lips and a _damn_ good tongue. “My good, beautiful boy…”

Sylvain whines, dick twitching against Byleth’s leg, hips shaking with the effort of not humping against her. Byleth ducks her head to kiss Sylvain’s throat, fingers at the nape of his neck to guide him to bare it for her. He huffs out a sigh and brings a hand to the back of her head in turn, gentle but needy, letting her know he’s craving it. There are already bruises all across his neck, marks from her that he absolutely begs for, and his skin is salt and sweat against her lips.

Sylvain pulls back with a gasp and she cups her chin between her hands and kisses him full on the mouth, then, curling her hand around his stiff cock at the same time so she can draw his groan of pleasure into her own. Her tongue delves into his mouth, licking across his and drawing it into her mouth, punctuating it with a slow roll of her hips.

“Good boy,” she repeats when she pulls away, one hand on his cock as the other reaches for the small cup she’s been using, scooping some water mostly devoid of bubbles to rinse the suds from his head. He looks positively blissed out even from the kiss, so trusting and lovesick as he looks up at her and if her heart could beat, it would skip one.

Sweetly, she tips his chin up, nestling his face between her breasts and letting the water flow over his hair, rinsing it until all of the bubbles are gone.

He’s so different like this: less guarded, more serene. It’s hard to believe the man beneath her is the same one who once evaded angry boyfriends and flirted with anything whose heart beat out a pulse, not when he’s so pliant and complacent under her hands, not when he’s so singularly devoted to her, to _this_, to being a one-woman man in a way he never thought he’d be.

“Do you want to?” She asks, rubbing down against his cock, letting the blunt head of it part her cunt, letting him feel how slick and ready she is. She doesn’t think she’s wanted it _this_ bad in a while, thinks it’s been weeks since she’d spent the hours at the war table damp and hot against her panties thinking about the feel of him. “Or do you want to go lay in my bed?” 

“Whatever you want, By…” he answers, shaking his head, scattering droplets of water flying that make her jump. She shoves his shoulder playfully, lifting herself off of him with no small amount of reluctance, climbing out of the bath and bending to pick up her clothes. She knows the view she presents as he turns to watch her: bent over, legs lifted one after the other to step back into her shorts, her tits a tantalizing sight as she squeezes her tight shirt over them.

Sylvain watches her with a hunger he doesn’t even try to conceal, licking his lips as he looks at her… the pale green of the damp hair between her legs, the pretty pink of her cunt, the generous swell of her chest and her hard nipples. Hypnotized, he climbs out as well, moving to stand before her for approval, leaning down to capture her mouth in a kiss that he hopes can even convey half of how bad he wants her. Her tongue feels good against his lips, in his mouth, controlling in a way that _isn’t – _sweetly, gently giving orders he finds much more fun to obey than battle commands.

She dries him with a soft cloth and leaves him standing before her, cock heavy against his thigh. She could have him right here, she knows (and it wouldn’t be the first time), urge him back into the bath or down to the steamy tile floor, take her pleasure and give him his. They’re beyond that, though. In a way. He’s not just a quick fuck to burn off the tension of a hard-won battle, and she’s not just another half-finished conquest of his youth. They’re taking this all the way to end, beside Dimitri with their hands clasped, her magic and the creator’s blade striking down the Kingdom’s enemies and healing its wounds. This is the way that Sylvain wants to cope with old friends at the deadly end of his lance, the years he’d imagined spent in revelry spent in a war council instead: coming to her and going slack in her arms, falling into how good it is to be _hers_.

Thankfully, she’d taken up her old room at the monastery when they’d returned, and like it was pre-ordained for this very purpose… it’s right beside the building housing the sauna and the baths. They hurry into her room before anyone can see them (not that they are bothering to keep secrets, not when he’s adorned with her father’s ring on his finger and a collar of her love bruises around his neck) but because if either of them has to talk to any friends or allies, they might go mad from wanting.

He obediently spreads his legs when Byleth pushes him down onto her bed, leaving his cock and balls on full display. His cock is proud and thick, flushed red at the tip and he looks so ready - his face is flushed and needy, his eyes begging for a treat, scraps of her attention fed from sweet fingers.

She lowers herself astride his waist with the same fluidity she has in battle and asks again, “Do you want to?”

Sylvain bites his lip and nods, his hands coming to rest on her hips. “More than you know, professor,” he answers, calling her title with a wink. She nods her approval and rises up, a hand curling again around the thick base of his cock to hold him steady as she lowers herself onto it. It’s an easy slide, familiar and comforting, and the way his eyes still roll back in his head like it’s the first time, every time, makes her clench tight around him. Just that small reaction, the way he exhales _fuck_ may be enough to send her over the edge every time. Thank the goddess one of them has self-control, that one of them doesn’t lose their mind the minute they start.

Her body is so warm beneath his hands, soft and supple skin over toned muscle. She’s so powerful, with her sword and her magic and the sheer _energy_ she has. His thumbs rub circles in the hollows of her hips across skin unmarked and scarred alike and he thinks that even if he’s never been a religious man, he’d go down on his knees every day and thank whatever deity listened for Byleth.

“Good boy…” she says, stuttering as she rocks her hips to work him deeper, gasping when he snaps his hips up to meet hers. His cock feels huge inside of her and her vision blurs for just a moment, breath hitching when it bumps against somewhere deep. “You’re so _good_.”

Sylvain offers a lazy grin and nods, looking up at her with puppy eyes. The look on his face so clearly begs _praise me, _and his crooked grin becomes a lopsided, blissful smile. He urges her on with, “Yeah, Byleth…?”

She runs her hands along his body on display beneath her, over his abs honed by years of training with Felix, over his chest with its scattering of hair grown over the years, over his skin still warm from the bath. She’s still never quite adjusted to her name falling from Sylvain’s lips, so personal and private and impossibly erotic, squeezing her legs tighter together as she rides him. “Such a good boy. Your cock feels so good, do you know that? I dream of you when I can’t have it.”

Sylvain whimpers as her hands find his nipples, eager nubs on his toned chest, pinching and rolling them between her fingers until he tips his head back onto her pillow and cries out in earnest. She’s been with men before him - hardened mercenaries who were good for fucking out the adrenaline high of battle, older men with rough hands and satisfying cocks, younger men who praised _every_ move she made when it came to her hand cradling their balls or her tongue laving up their cocks - but never a man whose nipples were as sensitive as Sylvain’s, never a man who was as much _fun_ to fuck as Sylvain. She thought it was horribly erotic, making him moan like this, making his lips part for pant after pant, hips finding an easy rhythm to meet every move she made even while he was letting her lead.

“You like that, don’t you?” She asks, leaning down to kiss his chest, tongue darting out to tease a hardened nipple before she bites it, hips rolling as he snaps his hips up against her. “So cute, Sylvain… just like a good puppy. This is what you like, isn’t it? To lay back and get his belly rubbed and his cock squeezed?”

He nods, hot whiskey eyes half-open, propelled only by the desperate desire she knows he has to watch her love his cock. She kisses him deep, breathing in his moan before she rises back up, re-adjusting her position and dragging her hands up her body, fingers mimicking his finger teasing her clit and Sylvain groans his approval. “You know that’s… all I need…really… “

Words are failing him, too focused on the feel of her around him. “Does my cunt feel good, Sylvain?” she asks.

His nod this time is frantic, enthusiastic and honest. His hands come to her tits, grabbing almost blindly in his pleasure, squeezing them appreciatively before a hand drags down her stomach, fingers trailing through the wiry pale green hair slick with her desire, fingers stopping just shy of her clit and glancing at her for approval. He wants to touch it – goddess, he can see it where her cunt is spread around him, so sweet and hard and just _begging_ to be touched – but he wants her to ask him to, to _tell him to_.

“Go on,” she nods, and Sylvain’s thumb obediently takes up its position, rubbing in time with the grind of her hips. Sylvain has never been _bad, _but teaching him things like this, like his fingers on her clit, have made him _perfect_. The perfect puppy, one that doesn’t even need to be leashed or even collared but _wants to be_, one who trails along behind her and into their bed without her even asking, one who thinks about both of them instead of just himself.

_Fuck_, he’s good. Every drag of his thumb works Byleth closer to the edge, every snap of his hips pressing his thick cock deep inside of her makes her feel half-delirious with pleasure. There’s a sweet, warm ache curling low in her belly, hot and heavy and telling her she’s going to come. Her entire body feels pulled like a bowstring, pulled taut and ready to snap when she finally crests this wave of pleasure. He’s close, too; she can feel it in his body, thighs shaking beneath her to match her own, his body tense.

“I want… “ he starts, the words dissolving into another groan of pure pleasure, and she wonders if what she thinks he wants is truly what he wants. He’s going to if she doesn’t get him out of her, soon… spill inside of her, fill her up with the creamy cum she can’t get enough of and she realizes when she looks at him that he’s _going to_. His face is nothing but sincere when he looks up at her, chest rising and falling in a series of desperate pants as he fucks up into her, his fingers relentless on her clit until she’s gasping, coming, her fingers digging into Sylvain’s belly as she struggles to support herself on shaking thighs.

Once, this would have scared him. There was a reason she’d been the first woman he’d truly bedded, too fearful of a child that may leave him tricked into a marriage where he was a trophy, resistant to the very idea of being used a stud horse for his coveted noble seed. Now, his hands grab her hips when she tries to pull him out before he can finish, hand splayed on her belly as his fingers work her clit, threatening to send her cresting over the edge again.

“You spilled inside,” she coos, rubbing the place they’re connected, fingers coming away sticky with her own slickness and Sylvain’s cum. Sylvain nods slowly, surely, a small smile on his lips. “Sure did, professor.”

Byleth smiles, leaning down to plant a kiss just above his nipple, then his neck, then his jaw. Smiling against his skin, she presses one last kiss to his cheek and praises, “Good puppy.”

**Author's Note:**

> I am [tsunderestorm](twitter.com/tsunderestorm) on twitter! ♥


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